PI Frederick Miller, Chief Environmental Autoimmunity Group, NIEHS, NIH Co-investigators Ed Chan, Univ. Florida, Minoru Satoh, Univ, Florida, Dori Germolec, NIEHS, Christine Parks, NIEHS, Charles Dillon, CDC and Darryl Zeldin, NIEHS 1. Hypotheses and Specific Aims: Hypothesis 1 - Autoantibodies are more frequent in the general population than previously suspected, increase with age, and are more prevalent in females and in minority ethnic groups. Hypothesis 2 - Autoantibody levels correlate with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) serum levels. Hypothesis 3 - Autoantibodies are not associated with exposure to xenobiotics without immunotoxic effects, but are associated with exposures to other selected immune-disrupting xenobiotics that could inform future epidemiologic investigations relating to the causes of autoimmune diseases. 2. Funding Funding will be provided by intramural funds from NIEHS, NIH - estimated costs are listed below: Cost estimates: $32,286 CDC sample retrieval